Imaging systems can create blurry or unreadable images if the camera system shakes while the image is being captured. This is particularly problematic in digital symbol reading systems, where it is important to correctly capture a digital image containing data to be decoded. An example of such systems are those used to read 2-dimensional bar codes.
Many systems have long existed for attempting to correct this problem. These systems typically compensate by moving a detection array, such as a charge coupled device (CCD) in response to movements of the camera system. Other prior systems move the camera lens in response to shaking to compensate for movement of the camera.
A typical prior art such compensation system is shown in FIG. 1. In operation, if the camera shakes, summer 108 will output a signal representing the rate of change of the camera position with respect to time. Integrator 109 then generates a signal X representing the change in position of the camera. This signal X controls a compensator 110, which in turn is fed back through amplifier 101 for control of variable frequency (“V/F”) converter 102.
That output frequency of V/F converter 102 is fed to driver 103 which controls the stepping motor 104 in a manner that is proportional to the frequency output by V/F converter 103. The stepping motor 104 then controls camera module 105, which includes an image sensor and a gyroscope sensor 107 as shown. The signal from stepping motor 104 moves the image sensor to correct for the camera shake. Thus, due to the feedback loop shown, the greater the amplitude of the camera shake, the greater the correction will be.
While the above system provides reasonable performance, one problem with it is that the V/F converter is a relatively expensive and complicated component to manufacture and control. Accordingly, the system is more costly than it needs to be, and is also subject to failures. The output frequency must track an input error signal relatively accurately.
In view of the above, there exists a need in the art for a more efficient and simpler design to compensate for camera shake in a digital imaging system.